Nothing has actually changed?
The toy market is under continual change and every child is borne into the context and culture of their era.
There is also opportunity cost. Had I listened to my mother on that fateful day in Woolworths, we could have moved ten foot one way to have bought ourselves sports gear. Since neither my sister or myself can catch a ball, maybe we should have got into badminton, table tennis or football. But we denied ourselves that opportunity because we bought yet more LEGO.
Things were different in period in the USA, particularly for middle class kids, where the abundance of toys was entirely different. My American counterparts of the period had 10x the toys we had. Not jealous, just saying.
As an outsider looking in on American culture in general, there is too much infantilisation going on for my liking. Adults going to Disneyland with no kids in tow, adults watching MARVEL movies with no kids in tow, adults eating McDonalds, adults eating cereal with cartoon characters on the box, adults drinking Coca Cola and so on. Even the car culture is somewhat infantile.
Why has American gone the wrong way, to retreat into a nine-year-old 'inner America'?
Going back a bit, the finest literature came out of the USA, not yet more infantile cruft. Something is amiss.
We have been here before. After WW2, plenty of men returned to retreat into their inner nine year old selves, which kept model trains going for a while after the kids lost interest. But the adults changed the hobby from playing trains to this micro-realistic world with running trains becoming a rarity, rather than what it was all about. This was their coping mechanism, and I understand that.